Players need 15 items to fill the Compost Bin, which they can then close to start the rotting process.

Players must use 15 supercompost-compatible items in the compost bin to make supercompost - even one incompatible item will make the whole contents into regular compost. This is the same when making rotten tomatoes. A message will pop up warning the player if they choose to impurify their compost bin.

After the 15 September2010update, compost bins were updated so that when examined players could see how full they were, from empty through to completely full (0-15 items). Since different players fill the compost bins with different quantities of items, the examine text is different for each player depending on what they have put inside.